Semiconductor device and method of manufacturing the same

ABSTRACT

The semiconductor device which has a memory cell including the TMR film with which memory accuracy does not deteriorate, and its manufacturing method are obtained. A TMR element (a TMR film, a TMR upper electrode) is selectively formed in the region which corresponds in plan view on a TMR lower electrode in a part of formation area of a digit line. A TMR upper electrode is formed by 30-100 nm thickness of Ta, and functions also as a hard mask at the time of a manufacturing process. The interlayer insulation film formed from LT-SiN on the whole surface of a TMR element and the upper surface of a TMR lower electrode is formed, and the interlayer insulation film which covers the whole surface comprising the side surface of a TMR lower electrode, and includes LT-SiN is formed. The interlayer insulation film which covers the whole surface and includes SiO 2  is formed.

CONTINUING DATA INFORMATION

This is a Divisional Application of U.S. application Ser. No.11/593,548, filed Nov. 7, 2006 now U.S. Pat. No. 7,605,420, the contentof which is hereby incorporated by reference into the presentapplication.

FOREIGN PRIORITY DATA INFORMATION

The present application claims priority from Japanese patent applicationNo. 2005-328845 filed on Nov. 14, 2005, and No. 2006-276259 filed onOct. 10, 2006, the contents of which are hereby incorporated byreference into this application.

1. Field of the Invention

This invention relates to a semiconductor device which has memorydevices, such as TMR (Tunneling Magneto Resistance), and itsmanufacturing method.

2. Description of the Background Art

MRAM is a memory which holds data by storing information in the spinwhich an electron has, and the circuit is formed so that the randomaccess is possible. There is a type which uses GMR (Giant MagnetoResistance), TMR, and CMR (Colossal Magneto Resistance) as a basicphysical phenomenon.

TMR is a type using the resistance change phenomenon observed in thestructure which sandwiches an insulating layer with the magnetic film oftwo layers. In the state of the spin of the up-and-down magnetic layerwhich sandwiches an insulating layer, the current (namely, resistance ofTMR) which flows through an upper magnetic layer—an insulating layer—abottom magnetic layer changes. Resistance becomes small when two spinstates of an up-and-down magnetic layer are parallel, and if it isantiparallel, resistance becomes large. This change in resistance canperform information storage. There is Patent Reference 1 as literaturewhich disclosed the magnetic memory equipment which has such a TMRelement, and its manufacturing method. There is also structure called aMTJ (Magnetro-Tunneling Junction) element as an element of the samestructure as TMR. Hereafter, a “TMR element” includes an MTJ element notonly a TMR element but widely in a present application specification.

-   [Patent Reference 1] Japanese Unexamined Patent Publication No.    2003-243630

SUMMARY OF THE INVENTION

However, when the lower lead-out electrode (LS (Local Strap)) of the TMRfilm (up-and-down magnetic layer which sandwiches an insulating layer)which forms a TMR element is processed, there was a problem that theleakage current through the magnetic layer of the upper and lower sidesof a TMR film occurs, and it becomes impossible for a TMR film to securethe predetermined rate of a resistance change, and normal storageoperation became impossible and memory accuracy will deteriorate by thedeposition of the foreign substance by etching deposition material tothe up-and-down magnetic layer of a TMR film.

This invention was made in order to solve the above-mentioned problem.It aims at obtaining the semiconductor device which has a memory cellincluding the TMR film with which memory accuracy does not deteriorate,and its manufacturing method.

The semiconductor device according to claim 1 concerning this inventionhas a memory cell which is formed over a semiconductor substrate andincludes a laminated structure of a TMR film and an upper electrodeformed in a portion over a lower electrode and the lower electrode; anantioxidant film which is formed covering an upper surface of the lowerelectrode, and a side surface of the TMR film at least, to the memorycell; and an oxide film formed over the antioxidant film.

The semiconductor device according to claim 6 concerning this inventionhas a memory cell which is formed over a semiconductor substrate andincludes a laminated structure of a TMR film and an upper electrodewhich were formed in a portion over a lower electrode and the lowerelectrode; a read wire which separates a predetermined distance in planview and is formed under the lower electrode from the TMR film; and ametal plug which is formed over the read wire and electrically connectsthe read wire and the lower electrode.

The semiconductor device according to claim 8 concerning this inventionhas a memory cell which is formed over a semiconductor substrate andincludes a laminated structure of a TMR film and an upper electrodewhich were formed in a portion over a lower electrode and the lowerelectrode; wherein the upper electrode is a hard mask layer which wasformed using the same material as the lower electrode, which hasconductivity, and whose thickness is 30-100 nm.

The manufacturing method of the semiconductor device according to thisinvention has the steps of (a) forming a laminated structure of a TMRfilm and an upper electrode which were formed in a portion over a lowerelectrode and the lower electrode over a semiconductor substrate; (b)patterning the upper electrode and the TMR film; (c) forming a firstantioxidant film covering the lower electrode, the upper electrode, andthe TMR film; (d) patterning the first antioxidant film and the lowerelectrode after the first antioxidant film has covered the upperelectrode and the TMR film; and (e) forming an oxide film in a wholesurface.

The manufacturing method of the semiconductor device according to thisinvention has the steps of (a) forming a read wire over a semiconductorsubstrate; (b) forming an interlayer insulation film over the read wire;(c) forming a via hole, penetrating the interlayer insulation film overthe read wire; (d) forming a metal plug, embedding the via hole; and (e)forming a laminated structure of a lower electrode, a TMR film, and anupper electrode over the interlayer insulation film comprising the viahole; wherein the lower electrode is electrically connected with theread wire via the metal plug, and further comprising a step of: (f)patterning the upper electrode and the TMR film; wherein the TMR filmafter patterning is formed, separating a predetermined distance in planview from the read wire.

The manufacturing method of the semiconductor device according to thisinvention has the steps of (a) forming a laminated structure of a lowerelectrode, a TMR film, and an upper electrode over a semiconductorsubstrate; (b) patterning the upper electrode; and (c) patterning theTMR film using the upper electrode as a hard mask layer.

The semiconductor device according to this invention has a firstinterlayer insulation film formed above a semiconductor substrate; alower layer wiring which penetrates the first interlayer insulation filmand is formed selectively; and a second interlayer insulation filmformed over the first interlayer insulation film including the lowerlayer wiring; wherein the second interlayer insulation film has a viahole where at least a part of the lower layer wiring constitutes abottom; and further comprising a lower electrode formed at a bottom anda side surface of the via hole, and over the second interlayerinsulation film; wherein the lower electrode is electrically connectedwith the lower layer wiring via the via hole; and further comprising aTMR element which is formed selectively over a portion over the lowerelectrode, and includes a laminated structure of a TMR film and an upperelectrode; and an insulating film formed over the lower electrodecomprising an inside of the via hole; wherein both the insulating filmand the lower electrode have a side surface over the second interlayerinsulation film in a uniform direction; and a side surface of the lowerelectrode corresponds in a uniform direction to a side surface of theinsulating film, or a side surface of the lower electrode is depressedfrom the insulating film.

The manufacturing method of the semiconductor device according to thisinvention has the steps of (a) forming a first interlayer insulationfilm above a semiconductor substrate; (b) forming a lower layer wiringselectively, penetrating the first interlayer insulation film; (c)forming a second interlayer insulation film over the first interlayerinsulation film including the lower layer wiring; and (d) forming a viahole, penetrating the second interlayer insulation film over the lowerlayer wiring; wherein a bottom of the via hole becomes at least a partof the lower layer wiring; and further comprising the steps of: (e)forming a lower electrode over a bottom and a side surface of the viahole, and the first interlayer insulation film; wherein the lowerelectrode is electrically connected with the lower layer wiring via thevia hole; and further comprising the steps of; (f) forming selectively aTMR element used as a laminated structure of a TMR film and an upperelectrode over the lower electrode over the second interlayer insulationfilm; (g) forming an insulating film over the lower electrode comprisingthe via hole; (h) forming a resist patterned over the insulating film;(i) etching simultaneously the lower electrode and the insulating filmby using the resist as a mask, and patterns the lower electrode and theinsulating film; and (j) removing the resist.

Since the upper surface of a lower electrode and the side surface of aTMR film are covered at least and the antioxidant film is formed, thesemiconductor device can suppress surely that the upper surface of alower electrode and the side surface of a TMR film oxidize, when anoxide film is formed on an antioxidant film. As a result, the memorycell which has a TMR film with which memory accuracy does notdeteriorate can be obtained.

Since a read wire and a lower electrode are electrically connected via ametal plug, a semiconductor device performs the effect which can form alower electrode with sufficient flatness and can form a memory cell withsufficient accuracy compared with the case where a read wire and a lowerelectrode are electrically connected directly.

An upper electrode can be used for a semiconductor device as a hardmask, and since the step which forms a hard mask separately becomesunnecessary, it can aim at simplification of a manufacturing process.Since the thickness of the upper electrode was formed by 30-100 nmcomparatively thin thickness, relief of the stress applied to a TMR filmat the time of formation of an upper electrode can be aimed at, and themagnetic property of a TMR film is not degraded. Since the upperelectrode and the lower electrode are formed using the same material,when etching a TMR film by using an upper electrode as a hard masklayer, a lower electrode can be operated as an etching stopper.

The manufacturing method of a semiconductor device forms the firstantioxidant film, covering the upper surface and the side surface of alower electrode, and the side surface of a TMR film at least at the step(c). So, when an oxide film is formed on the first antioxidant film at astep (e), it can suppress surely that the upper surface and the sidesurface of a lower electrode, and the side surface of a TMR filmoxidize. As a result, the memory cell which has a TMR film with whichmemory accuracy does not deteriorate can be obtained.

Since the via hole is embedded by the metal plug at the step (d) in themanufacturing method of a semiconductor device, the effect which canform a lower electrode with flatness sufficient on an interlayerinsulation film, without being influenced by a via hole, and can form amemory cell with sufficient accuracy is performed.

In a step (c), since the step which forms a hard mask separately byusing an upper electrode as a hard mask layer becomes unnecessary, themanufacturing method of a semiconductor device can aim at simplificationof a manufacturing process. Since the thickness of the upper electrodewas formed by 30-100 nm comparatively thin thickness, relief of thestress applied to a TMR film at the time of formation of an upperelectrode can be aimed at, and the magnetic property of a TMR film isnot degraded. Since the upper electrode and the lower electrode areformed using the same material, when etching a TMR film by using anupper electrode as a hard mask layer, a lower electrode can be operatedas an etching stopper.

As for the semiconductor device in this invention, the insulating filmis formed on the lower electrode in a via hole. So, since the lowerelectrode in a via hole is protected by the insulating film byprocessing a lower electrode simultaneously with processing of aninsulating film, in the manufacturing process after lower electrodeprocessing, the damage to the lower layer wiring under a via hole can beavoided, and improvement in the yield can be aimed at.

Since the side surface of a lower electrode corresponds in a uniformdirection to the side surface of an insulating film or becomes depressedfrom the insulating film, even if it processes an insulating film and alower electrode simultaneously, it does not have a bad influence on theworking shape of a lower electrode.

In a step (i), the manufacturing method of the semiconductor device inthis invention etched simultaneously the lower electrode and theinsulating film by having used resist as the mask, and has patterned thelower electrode and the insulating film. Therefore, since the lowerelectrode in a via hole is protected by the insulating film after thestep (i) execution, in a step (j) running phase, the damage to the lowerlayer wiring under a via hole can be avoided, and improvement in theyield of the completed semiconductor device can be aimed at.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing the planar structure of the memory cellpart of MRAM which is a semiconductor device of Embodiment 1 of thisinvention;

FIG. 2 is a cross-sectional view showing the A-A section of FIG. 1;

FIG. 3 is a cross-sectional view showing the section structure in allthe layers of MRAM of Embodiment 1;

FIGS. 4A to 26D are cross-sectional views showing the manufacturingmethod of MRAM of Embodiment 1;

FIG. 27 is a plan view showing the planar structure of the memory cellpart of MRAM which is a semiconductor device of Embodiment 2 of thisinvention;

FIG. 28 is a cross-sectional view showing the A-A section of FIG. 27;

FIG. 29 is a cross-sectional view showing the section structure in allthe layers of MRAM of Embodiment 2;

FIGS. 30A to 44D are cross-sectional views showing the manufacturingmethod of MRAM of Embodiment 2;

FIG. 45 is an explanatory diagram showing the outline of MRAM structure;

FIG. 46 is a cross-sectional view showing the detail of connectingrelation with the memory device of MRAM, upper Cu wiring, and lower Cuwiring;

FIGS. 47 to 49 are cross-sectional views showing LS step for acquiringvia hole LS connection structure;

FIG. 50 is a cross-sectional view showing the structure of the memorycell part of MRAM which is a semiconductor device of Embodiment 3 ofthis invention;

FIG. 51 is a cross-sectional view showing the effect of thesemiconductor device of Embodiment 3;

FIG. 52 is graph which shows the coercive force of the TMR element tothe forming temperature of an insulating film;

FIG. 53 is graph which shows the anisotropic magnetic field of a TMRelement to the forming temperature of an insulating film;

FIGS. 54 and 55 are cross-sectional views showing the effect of thesemiconductor device of Embodiment 3;

FIG. 56 is a cross-sectional view showing other modes of Embodiment 3;and

FIGS. 57 to 63B are cross-sectional views showing a part ofmanufacturing method of MRAM of Embodiment 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

(Structure)

FIG. 1 is a plan view showing the planar structure of the memory cellpart of MRAM which is a semiconductor device of this embodiment of theinvention 1, and FIG. 2 is a cross-sectional view showing the A-Asection of FIG. 1.

As shown in FIG. 1, TMR film 29 is assuming the lengthwise form in whichfour angles were rounded in plan view. As shown in FIG. 2, TMR lowerelectrode 28 is formed under TMR film 29, and TMR upper electrode 31 isformed on TMR film 29. Memory cell MC includes these TMR lowerelectrodes 28, TMR films 29, and TMR upper electrodes 31. Forconvenience of explanation, TMR film 29 and TMR upper electrode 31 maybe combined in this specification, and it may be expressed as TMRelement 5. TMR film 29 includes the laminated structure of aferromagnetic layer, a nonmagnetic layer, and a ferromagnetic layer fromthe upper part, for example. A ferromagnetic layer includes the magneticfilm which includes NiFe, CoFeB, and CoFe, for example, and anonmagnetic layer includes, for example an alumina film or magnesiumoxide.

FIGS. 3A, 3B and 3C are cross-sectional views showing the sectionstructure in all the layers of MRAM of Embodiment 1. FIG. 3A isequivalent to the A-A section of FIG. 1, FIG. 3B is equivalent to theB-B section of FIG. 1, and FIG. 3C is equivalent to the C-C section ofFIG. 1. Hereafter, the structure of MRAM of Embodiment 1 is explainedwith reference to FIG. 1-FIG. 3C.

Element isolation region 2 is selectively formed in the upper layerportion of semiconductor substrate 100, and well region 1 w betweenelement isolation regions 2 and 2 functions as a transistor formationarea. In the above-mentioned transistor formation area, source/drainregions 14 and 14 of a pair are formed across channel region 1 c, gateinsulating film 11 and gate electrode 12 are laminated on channel region1 c, and sidewall 13 of 2 layer structure is formed in the side surfaceof gate electrode 12. Cobalt silicide region 15 is formed onsource/drain region 14 and gate electrode 12, respectively.

MOS transistor Q1 for selection at the time of read-out is formed bythese channel region 1 c, gate insulating films 11, gate electrodes 12,sidewalls 13, and source/drain regions 14.

Whole semiconductor substrate 100 upper part surface including MOStransistor Q1 is covered, and interlayer insulation film 16 whichincludes an oxide film of SiO₂ etc. is formed. Interlayer insulationfilm 16 is penetrated, contact plug 17 is formed, and it electricallyconnects with one cobalt silicide region 15 of source/drain regions 14and 14 of a pair.

On interlayer insulation film 16, nitride film 41, and interlayerinsulation film 18 which includes an oxide film are laminated, Cu wiring19 is formed selectively penetrating nitride film 41 and interlayerinsulation film 18, and Cu wiring 19 of 1 is electrically connected withcontact plug 17.

On interlayer insulation film 18 including Cu wiring 19, nitride film42, and interlayer insulation film 20 and 21 which includes an oxidefilm are laminated. Micropore 52 formed by penetrating nitride film 42and interlayer insulation film 20 and wiring hole 62 formed bypenetrating interlayer insulation film 21 are formed, and Cu wiring 22is formed embedding in micropore 52 and wiring hole 62. Cu wiring 22 iselectrically connected with Cu wiring 19 (Cu wiring 19 of above 1electrically connected with contact plug 17).

On interlayer insulation film 21 including Cu wiring 22, nitride film43, and interlayer insulation film 23 and 24 which includes an oxidefilm are laminated. Micropore 53 is formed penetrating nitride film 43and interlayer insulation film 23, wiring hole 63 is formed penetratinginterlayer insulation film 24, and Cu wiring 25 (read wire 25 r, digitline 25 d) is formed embedding in micropore 53 and wiring hole 63. Readwire 25 r is electrically connected with Cu wiring 22 (Cu wiring 22located on contact plug 17).

Interlayer insulation film 26 a which includes a nitride film, andinterlayer insulation film 26 b which includes an oxide film arelaminated on interlayer insulation film 24 including Cu wiring 25. Viahole 9 is formed in interlayer insulation films 26 a and 26 b whichcorrespond to a part of formation area of read wire 25 r in plan view.By forming TMR lower electrode 28 selectively on interlayer insulationfilm 26 b, and the bottom and the side surface of via hole 9, TMR lowerelectrode 28 is electrically connected with read wire 25 r. Since TMRlower electrode 28 includes tantalum (Ta) with a near lattice spacing ofa crystal lattice with TMR film 29, it can reduce distortion generatedon TMR film 29. TMR lower electrode 28 may be called the lead-out wiring(LS (Local Strap)) which electrically connects read wire 25 r and TMRfilm 29.

TMR element 5 (TMR film 29, TMR upper electrode 31) is selectivelyformed in the region which corresponds in plan view on TMR lowerelectrode 28 in a part of formation area of 25 d of digit lines. TMRupper electrode 31 is formed by the thickness of 30-100 nm of tantalum(Ta), and functions also as a hard mask at the time of a manufacturingprocess.

And interlayer insulation film 30 including LT (Low Temperature)-SiN onthe whole surface of TMR element 5 and the upper surface of TMR lowerelectrode 28 is formed. Interlayer insulation film 32 which covers thewhole surface comprising the side surface of TMR lower electrode 28, andincludes LT-SiN is formed. Interlayer insulation film 33 which coversthe whole surface and includes SiO₂ is formed.

Cu wiring 34 used as a bit line is selectively formed in the upper layerportion of interlayer insulation film 33. In the part of the region inwhich TMR element 5 is formed in plan view, interlayer insulation film30, interlayer insulation film 32, and interlayer insulation film 33 arepenetrated, and via hole 40 is formed, By embedding Cu wiring 34 also inthis via hole 40, Cu wiring 34 and TMR upper electrode 31 areelectrically connected. And passivation film 35 film is formed on thewhole surface on interlayer insulation film 33 including Cu wiring 34.

MRAM of Embodiment 1 is assuming the above structures and has the firstand second feature shown below.

The first feature is that it has covered all of the upper surface andthe side surface of TMR lower electrode 28, and the side surface of TMRelement 5 with interlayer insulation film 32 in addition to interlayerinsulation film 30 formed from LT-SiN.

Although interlayer insulation films 30 and 32 which include LT-SiNfunction as an antioxidant film at the time of depositing interlayerinsulation film 33 which includes SiO₂, in the case of only interlayerinsulation film 30, when the side surface of TMR film 29 becomes thin,it is sometimes difficult to function sufficiently as an antioxidantfilm. However, in Embodiment 1, sufficient antioxidant function can beexhibited by protecting TMR film 29 with interlayer insulation film 30and 32 of two layers. Since the upper surface and the side surface ofTMR lower electrode 28 are covered and interlayer insulation film 30 and32 is formed, sufficient antioxidant function can be exhibited also toTMR lower electrode 28.

In addition, since interlayer insulation film 30 has covered all theside surfaces of TMR element 5 at the time of processing of TMR lowerelectrode 28, by protecting surely the side surface of memory cell MC,especially TMR film 29, it can prevent the foreign substance by etchingdeposition material adhering, and leakage current occurring.

Since LT-SiN is formed at comparatively low temperature of less than300° C., the magnetic property of TMR film 29 is not degraded at thetime of manufacture of interlayer insulation film 30 and 32.

The second feature is the point which made it possible to use as a hardmask at the time of a manufacturing process by using Ta of the thicknessof 30-100 nm as TMR upper electrode 31.

According to this second feature, TMR upper electrode 31 can be used asa hard mask, the step which forms a hard mask separately becomesunnecessary, and simplification of a manufacturing process can be aimedat. Since the thickness of TMR upper electrode 31 was formed by thethickness of comparatively thin 30-100 nm, relief of the stress appliedto TMR film 29 at the time of formation of TMR upper electrode 31 can beaimed at, and the magnetic property of TMR film 29 is not degraded.

By both forming TMR lower electrode 28 and TMR upper electrode 31 withthe same material (Ta), when processing TMR film 29 by using TMR upperelectrode 31 as a mask, TMR lower electrode 28 functions as a stopper,and the effect that TMR film 29 can be formed with sufficient patterningaccuracy is acquired.

(Manufacturing Method)

FIG. 4A-FIG. 26D are the cross-sectional views showing the manufacturingmethod of MRAM of Embodiment 1. In these drawings, “A” is equivalent tothe A-A section of FIG. 1, “B” is equivalent to the B-B section of FIG.1, and “C” is equivalent to the C-C section of FIG. 1. “D” in FIG.12A-FIG. 26D shows the section of the peripheral circuit part.Hereafter, the manufacturing method of MRAM of Embodiment 1 is explainedwith reference to these drawings.

First, as shown in FIGS. 4A to 4C, element isolation region 2 isselectively formed in the upper layer portion of semiconductor substrate100. The upper layer portion of semiconductor substrate 100 betweenelement isolation regions 2 and 2 becomes active region 1 in which atransistor etc. is formed.

And as shown in FIGS. 5A to 5C, well region 1 w is formed in the upperlayer portion of semiconductor substrate 100 by introducing the impurityof the first conductivity type.

Next, as shown in FIGS. 6A to 6C, gate insulating film 11 is formed onwell region 1 w, and gate electrode 12 is selectively formed on gateinsulating film 11. The front surface of well region 1 w under gateelectrode 12 is specified as channel region 1 c.

Then, as shown in FIGS. 7A to 7C, the impurity of the secondconductivity type (conductivity type opposite to the first conductivitytype) is implanted and diffused in self align to gate electrode 12, andafter forming sidewall 13 of 2 layer structure in the side surface ofgate electrode 12, the impurity of the second conductivity type isimplanted and diffused in self align to gate electrode 12 and sidewall13. This forms source/drain regions 14 and 14 of the pair which has anextension region near the channel region 1 c. As a result, MOStransistor Q1 which includes channel region 1 c, gate insulating film11, gate electrode 12, and source/drain region 14 is formed.

Next, as shown in FIGS. 8A to 8C, cobalt silicide region 15 is formed,respectively on source/drain regions 14 and 14 and the front surface ofgate electrode 12.

Then, as shown in FIGS. 9A to 9C, interlayer insulation film 16 isformed in the whole surface, interlayer insulation film 16 is penetratedand contact plug 17 is formed selectively. This contact plug 17 iselectrically connected with one cobalt silicide region 15 of thesource/drain regions 14 and 14 of a pair.

As shown in FIG. 10, nitride film 41 and (it is an oxide film)interlayer insulation film 18 are laminated on the whole surface,nitride film 41 and interlayer insulation film 18 are penetrated on it,and Cu wiring 19 is selectively formed in it. As a result, a part of Cuwiring 19 is electrically connected with contact plug 17. Thus, Cuwiring 19 which is a first layer metal wiring is formed.

Then, as shown in FIGS. 11A to 11C, nitride film 42, and interlayerinsulation films 20 and 21 (it is an oxide film) are laminated by thewhole surface, nitride film 42 and interlayer insulation film 20 arepenetrated on it, and micropore 52 is selectively formed in it.Interlayer insulation film 21 on a region including micropore 52 ispenetrated, wiring hole 62 is formed selectively, after that, micropore52 and wiring hole 62 are embedded, and Cu wiring 22 is formed. Cuwiring 22 is electrically connected with Cu wiring 19 (Cu wiring 19electrically connected with contact plug 17). Thus, Cu wiring 22 whichis a second layer metal wiring is formed using damascene technology.

Then, as shown in FIGS. 12A to 12D, nitride film 43 and interlayerinsulation films (it includes an oxide film) 23 and 24 are formed,nitride film 43 and interlayer insulation film 23 are penetrated on thewhole surface, and micropore 53 is selectively formed in it. Interlayerinsulation film 24 on a region including micropore 53 is penetrated, andwiring hole 63 is formed selectively. Then, micropore 53 and wiring hole63 are embedded, and Cu wiring 25 (read wire 25 r, digit line 25 d) isformed. And read wire 25 r is electrically connected with Cu wiring 22.Thus, Cu wiring 25 which is a third layer metal wiring is formed usingdamascene technology.

As shown in FIG. 12D, also in a peripheral region, MOS transistor Q2equivalent to MOS transistor Q1 is formed on semiconductor substrate100, Cu wiring 19, Cu wiring 22, and Cu wiring 25 are formed in eachfirst-third layer metal wiring.

Then, as shown in FIGS. 13A to 13D, interlayer insulation films 26 a and26 b are formed in the whole surface, the portion on the region of readwire 25 r in a memory cell part is penetrated, and via hole 9 is formedselectively.

And as shown in FIGS. 14A to 14D, the layer which should constitute TMRlower electrode 28, TMR film 29, and TMR upper electrode 31 is laminatedon the whole surface. On this occasion, TMR lower electrode 28 iselectrically connected with read wire 25 r by forming TMR lowerelectrode 28 in the bottom and the side surface of via hole 9.

On this occasion, by forming the thickness of TMR upper electrode 31 by30-100 nm comparatively thin thickness, relief of the stress applied toTMR film 29 at the time of formation of TMR upper electrode 31 can beaimed at, and the magnetic property of TMR film 29 is not degraded. TMRlower electrode 28 and TMR upper electrode 31 make Ta constructionmaterial, as mentioned above, for example, they are formed of asputtering technique.

Then, as shown in FIGS. 15A to 15D, after patterning TMR upper electrode31 using the patterned resist which is not illustrated, it etches to TMRfilm 29 by making patterned TMR upper electrode 31 into a hard mask, andTMR element 5 is completed TMR lower electrode 28 including the same Taas TMR upper electrode 31 functions as an etching stopper in the case ofetching.

Thus, since the step which forms a hard mask separately becomesunnecessary by using TMR upper electrode 31 as a hard mask,simplification of a manufacturing process can be aimed at.

There is also no degradation of the magnetic film by ashing and thecleaning treatment for resist removal of TMR film 29 without thedeposition material of the organic substance system which worsens anelement characteristic adhering to the side wall of TMR film 29 like atthe time of etching with a resist mask.

Next, as shown in FIGS. 16A to 16D, interlayer insulation film 30 whichincludes LT-SiN is formed in the whole surface by the low temperaturecondition less than 300° C., and as shown in FIGS. 17A to 17D, resist 45patterned so that only the formation area of a memory cell might becovered is formed.

And as shown in FIGS. 18A to 18D, by etching TMR lower electrode 28 andinterlayer insulation film 30 by using patterned resist 45 as a mask,TMR lower electrode 28 is patterned, and as shown in FIGS. 19A to 19D,resist 45 is removed. Here, after etching interlayer insulation film 30by using patterned resist 45 as a mask and removing resist 45, TMR lowerelectrode 28 may be patterned by making interlayer insulation film 30into a hard mask. Hereby, TMR lower electrode 28 can be patterned stillwith high precision.

Next, as shown in FIGS. 20A to 20D, interlayer insulation film 32 whichincludes LT-SiN is formed in the whole surface by the low temperaturecondition less than 300° C. As a result, the side surface region of TMRfilm 29 and TMR lower electrode 28 are covered with interlayerinsulation films 30 and 32.

Next, as shown in FIGS. 21A to 21D, interlayer insulation film 33 whichincludes SiO₂ is formed in the whole surface. On this occasion, sincethe side surface region of TMR film 29 is covered with interlayerinsulation films 30 and 32, an antioxidant function can fully beexhibited at the time of formation of interlayer insulation film 33.Therefore, TMR film 29 is not damaged at the time of formation ofinterlayer insulation film 33. Since the upper surface and the sidesurface of TMR lower electrode 28 are covered and interlayer insulationfilms 30 and 32 are formed, sufficient antioxidant function can beexhibited also to TMR lower electrode 28.

Since LT-SiN which is a forming material of interlayer insulation films30 and 32 is formed by low temperature condition of comparatively below300° C., the magnetic property of TMR film 29 is not degraded.

Then, as shown in FIGS. 22A to 22D, flattening of the interlayerinsulation film 33 is done by performing CMP treatment to interlayerinsulation film 33.

Then, as shown in FIGS. 23A to 23D, via hole 39 which penetratesinterlayer insulation film 33 is formed at the upper part of TMR element5. As shown in FIG. 23D, via hole 49 is formed in the upper layer of apart of Cu wiring 25 in a peripheral region.

And as shown in FIGS. 24A to 24D, etching removal of the interlayerinsulation film 33 is selectively done to bit line formation. On thisoccasion, etching removal also of the interlayer insulation films 30 and32 under via hole 39 is done, and via hole 40 is formed. Etching removalof the interlayer insulation films 30 and 32 under via hole 49 is done,and via hole 50 is formed.

Next, as shown in FIGS. 25A to 25D, a bit line is formed by embedding Cuwiring 34 to the region which did etching removal of the interlayerinsulation film 33 comprising via holes 40 and 50. As a result, in amemory circuit region, Cu wiring 34 is electrically connected with TMRelement 5 (TMR upper electrode 31) via via hole 40, and Cu wiring 34 iselectrically connected with Cu wiring 25 in a peripheral circuit area.Thus, Cu wiring 34 which is a fourth layer metal wiring is formed.

Finally, as shown in FIGS. 26A to 26D, MRAM (a peripheral circuit isincluded) of Embodiment 1 is completed by forming passivation film 35 inthe whole surface.

Although the example which forms memory cell circuits (memory cell MC, abit line (Cu wiring 34), etc.) in a third layer and a fourth layer metalwiring was shown in Embodiment 1, it may be made to form a memory cellcircuit in a part for a first layer and a second layer metal wiringpart. It may form from five or more layers.

Embodiment 2

(Structure)

FIG. 27 is a plan view showing the planar structure of the memory cellpart of MRAM which is a semiconductor device of Embodiment 2 of thisinvention, and FIG. 28 is a cross-sectional view showing the A-A sectionof FIG. 27.

FIGS. 29A to 29C are cross-sectional views showing the section structurein all the layers of MRAM of Embodiment 2, FIG. 29A is equivalent to theA-A section of FIG. 27, FIG. 29B is equivalent to the B-B section ofFIG. 27, and FIG. 29C is equivalent to the C-C section of FIG. 27.Hereafter, the structure of MRAM of Embodiment 2 is explained withreference to FIG. 27-FIG. 29C. Since the structure from semiconductorsubstrate 100 to Cu wiring 25 which is a third layer metal wiring, andthe structure from interlayer insulation film 33 to passivation film 35are the same as that of MRAM of Embodiment 1 shown by FIG. 1-FIG. 3C,explanation is omitted.

On interlayer insulation film 24 including Cu wiring 25, interlayerinsulation films 26 a and 26 b are laminated, via hole 9 is formed ininterlayer insulation films 26 a and 26 b which correspond to a part offormation area of read wire 25 r in plan view, this via hole 9 is filledup, and Cu plug 10 is formed.

TMR lower electrode 28 is selectively formed on interlayer insulationfilm 26 b including Cu plug 10. Therefore, TMR lower electrode 28 iselectrically connected with read wire 25 r via Cu plug 10. TMR lowerelectrode 28 includes tantalum (Ta) in order to take the consistency ofa crystal lattice with TMR film 29. TMR lower electrode 28 may be calledthe lead-out wiring (LS (Local Strap)) which electrically connects readwire 25 r and TMR film 29.

TMR element 5 (TMR film 29, TMR upper electrode 31) is selectivelyformed in plan view on TMR lower electrode 28 to the regioncorresponding to a part of formation area of digit line 25 d. TMR upperelectrode 31 is formed by 30-100 nm thickness of tantalum (Ta), andfunctions also as a hard mask at the time of a manufacturing process.

And interlayer insulation film 30 formed from LT-SiN is formed on thewhole surface of TMR element 5, and the upper surface of TMR lowerelectrode 28. The whole surface comprising a side surface of TMR lowerelectrode 28 is covered, and interlayer insulation film 32 whichincludes LT-SiN is formed. Interlayer insulation film 33 which coversthe whole surface and includes SiO₂ is formed.

MRAM of Embodiment 2 is assuming the above structures, has the first andsecond feature mentioned above like Embodiment 1, and performs the sameeffect as Embodiment 1.

MRAM of Embodiment 2 has the following third features. Cu plug 10 isembedded and formed in via hole 9, and the third feature is the point ofaiming at electric connection between TMR lower electrode 28 and readwire 25 r by this Cu plug 10.

Since via hole 9 is embedded by Cu plug 10 by having the third feature,the effect that TMR lower electrode 28 can be formed with sufficientflatness, without being influenced by via hole 9, and memory cell MC canbe formed with sufficient accuracy is performed.

Hereafter, the above-mentioned effect is explained as compared with thestructure of Embodiment 1. Since TMR lower electrode 28 is formed alsoin via hole 9 in the case of Embodiment 1, as the distance between theformation positions of via hole 9 and TMR element 5 becoming near, theflatness of TMR lower electrode 28 worsens under the influence of viahole 9.

On the other hand, with the structure of Embodiment 2, since Cu plug 10is embedded in via hole 9 and TMR lower electrode 28 is not formed invia hole 9, regardless of the distance of via hole 9 and TMR element 5,TMR lower electrode 28 can be formed with sufficient flatness. That is,the structure of Embodiment 2 is more suitable for microfabrication.

Other structures which form TMR element 5 in right above Cu plug 10(i.e., the upper part of read wire 25 r) are considered as a structurenear the structure of Embodiment 2. As opposed to TMR lower electrode 28being formed on Cu plug 10 with other structure described above, withthe structure of Embodiment 2, TMR lower electrode 28 is formed oninterlayer insulation film 26 b, and the structure of Embodiment 2 canform TMR lower electrode 28 with sufficient flatness. Since the distanceof digit line 25 d and TMR element 5 becomes far inevitably on therelation to which read wire 25 r is located directly under TMR element 5in the case of other structure described above, there is also a minussurface which a write-in defect tends to generate.

(Manufacturing Method)

FIG. 30A-FIG. 44D are the cross-sectional views showing themanufacturing method of MRAM of Embodiment 2. In these drawings, “A”shows the A-A section of FIG. 27, “B” shows the B-B section of FIG. 27,“C” shows the C-C section of FIG. 27, and “D” shows the section of theperipheral circuit part. Hereafter, the manufacturing method of MRAM ofEmbodiment 2 is explained with reference to these drawings.

After passing through the step shown by the FIG. 4A-FIG. 12D ofEmbodiment 1, as shown in FIG. 30, interlayer insulation films 26 a and26 b are formed in the whole surface, the portion on the region of readwire 25 r in a memory cell part is penetrated, and via hole 9 is formedselectively.

Then, as shown in FIGS. 31A to 31D, via hole 9 is filled using damascenetechnology, and Cu plug 10 is formed.

And as shown in FIGS. 32A to 32D, the layer which should constitute TMRlower electrode 28, TMR film 29, and TMR upper electrode 31 is laminatedon the whole surface. On this occasion, TMR lower electrode 28 iselectrically connected with read wire 25 r via Cu plug 10. By formingthe thickness of TMR upper electrode 31 by 30-100 nm comparatively thinthickness, relief of the stress which takes for TMR film 29 at the timeof formation of TMR upper electrode 31 can be aimed at, and the magneticproperty of TMR film 29 is not degraded. TMR lower electrode 28 and TMRupper electrode 31 make Ta construction material, as mentioned above,for example, they are formed of a sputtering technique.

Since TMR lower electrode 28 is not formed in via hole 9 as mentionedabove, TMR lower electrode 28 can be formed with flatness sufficient oninterlayer insulation film 26 b and Cu plug 10.

Then, as shown in FIGS. 33A to 33D, after patterning TMR upper electrode31, it etches to TMR film 29 by making patterned TMR upper electrode 31into a hard mask, and TMR element 5 is completed. TMR lower electrode 28formed by the same Ta as TMR upper electrode 31 functions as an etchingstopper in the case of etching.

Thus, by using TMR upper electrode 31 as a hard mask, the step whichforms a hard mask separately becomes unnecessary, and simplification ofa manufacturing process can be aimed at.

There is also no degradation of the magnetic film by ashing and thecleaning treatment for resist removal of TMR film 29 without thedeposition material of the organic substance system which worsens anelement characteristic adhering to the side wall of TMR film 29 like atthe time of etching with a resist mask.

Next, as shown in FIGS. 34A to 34D, interlayer insulation film 30 whichincludes LT-SiN is formed in the whole surface, and as shown in FIGS.35A to 35D, resist 45 patterned so that only the formation area ofmemory cell MC might be covered is formed.

And as shown in FIGS. 36A to 36D, by etching TMR lower electrode 28 andinterlayer insulation film 30 by using patterned resist 45 as a mask,TMR lower electrode 28 is patterned, and as shown in FIGS. 37A to 37D,resist 45 is removed.

Next, as shown in FIGS. 38A to 38D, interlayer insulation film 32 whichincludes LT-SiN is formed in the whole surface. As a result, while theside surface region of TMR film 29 is covered with interlayer insulationfilms 30 and 32, the side surface region of TMR lower electrode 28 iscovered with interlayer insulation film 32.

Next, as shown in FIGS. 39A to 39D, interlayer insulation film 33 whichincludes SiO₂ is formed in the whole surface. On this occasion, sincethe side surface region of TMR film 29 is covered with interlayerinsulation films 30 and 32, an antioxidant function can fully beexhibited at the time of formation of interlayer insulation film 33.Therefore, TMR film 29 is not damaged at the time of formation ofinterlayer insulation film 33.

In addition, since interlayer insulation film 30 has covered all theside surfaces of TMR element 5 at the time of processing of TMR lowerelectrode 28, it can prevent the foreign substance by etching depositionmaterial adhering, and leakage current occurring by protecting surelythe side surface of memory cell MC, especially TMR film 29.

Then, as shown in FIGS. 40A to 40D, flattening of the interlayerinsulation film 33 is done by performing CMP treatment to interlayerinsulation film 33.

Then, as shown in FIG. 41, via hole 39 which penetrates interlayerinsulation film 33 is formed at the upper part of TMR element 5. Asshown in FIG. 41D, via hole 49 is formed in the upper layer of a part ofCu wiring 25 in a peripheral region.

And as shown in FIGS. 42A to 42D, etching removal of the interlayerinsulation film 33 is selectively done to bit line formation. On thisoccasion, etching removal also of the interlayer insulation films 30 and32 under via hole 39 is done, via hole 40 is formed, etching removal ofthe interlayer insulation films 30 and 32 under via hole 49 is done, andvia hole 50 is formed.

Next, as shown in FIG. 43, a bit line is formed by embedding Cu wiring34 to the region which did etching removal of the interlayer insulationfilm 33 comprising via holes 40 and 50. As a result, in a memory circuitregion, Cu wiring 34 is electrically connected with TMR element 5 (TMRupper electrode 31) via via hole 40, and Cu wiring 34 is electricallyconnected with Cu wiring 25 in a peripheral circuit area. Thus, Cuwiring 34 which is a fourth layer metal wiring is formed.

Finally, as shown in FIGS. 44A to 44D, MRAM (a peripheral circuit isincluded) of Embodiment 2 is completed by forming passivation film 35 inthe whole surface.

Embodiment 3 Premise Technology

FIG. 45 is an explanatory diagram showing the outline of MRAM structure.As shown in the same drawing, a plurality of memory devices 102 arearranged at matrix form. Two or more upper Cu wiring 134 is formed alonga column direction (slanting horizontal direction in a drawing), itelectrically connects with memory device 102 at a column unit, two ormore lower Cu wiring 125 is formed along a row direction (slantinglongitudinal direction in a drawing), and it electrically connects withTMR element 105 per line.

FIG. 46 is a cross-sectional view showing the detail of the connectingrelation of memory device 102, and upper Cu wiring 134 and lower Cuwiring 125 (read wire 125 r, digit line 125 d). As shown in the samedrawing, the inside of oxide film 124 formed above semiconductorsubstrate 100 (it does not illustrate but see the FIG. 3 etc.) ispenetrated, and lower Cu wiring 125 is formed selectively. On oxide film124 including lower Cu wiring 125, silicon nitride film 126 a and oxidefilm 126 b are laminated. Via hole 109 (local via hole) is formed ininterlayer insulation films 126 a and 126 b which correspond to a partof formation area of read wire 125 r in plan view. By formingselectively TMR lower electrode 158 used as lead-out wiring (LS (LocalStrap)) on interlayer insulation film 126 b, and the bottom and the sidesurface of via hole 109, TMR lower electrode 158 is electricallyconnected with read wire 125 r.

TMR element 105 (TMR film 129, TMR upper electrode 131) is selectivelyformed in the region which corresponds in plan view on TMR lowerelectrode 158 in a part of formation area of digit line 125 d. Memorydevice 102 includes TMR element 105 and TMR lower electrode 158. TMRfilm 129 has the laminated structure of ferromagnetic layer 129 a,nonmagnetic layer 129 b, and ferromagnetic layer 129 c from upper part.

And oxide film 133 which covers the whole surface including TMR element105, and includes SiO₂ is formed.

Top Cu wiring 134 used as a bit line is selectively formed in the upperlayer portion of oxide film 133. Oxide film 133 is penetrated, and viahole 140 is formed at the region in which TMR element 105 is formed inplan view. By embedding upper Cu wiring 134 also in this via hole 140,upper Cu wiring 134 and TMR upper electrode 131 are electricallyconnected.

As mentioned above, a general structure (it is hereafter written as “viahole LS connection structure”) of electrically connecting lower Cuwiring 125 (read wire 125 r) and TMR element 105 (TMR film 129) byforming TMR lower electrode 158 in via hole 109 is shown in FIG. 46.

In order to acquire the structure shown by FIG. 46, it passes throughthe manufacturing process which generally includes the following(1)-(9).

(1) Deposit silicon nitride film 126 a and oxide film 126 b on oxidefilm 124 including lower Cu wiring 125.

(2) Form selectively via hole 109 which penetrates silicon nitride film126 a and oxide film 126 b.

(3) Deposit the metallic thin film used as TMR lower electrode 158 onoxide film 126 b comprising via hole 109.

(4) Deposit the formative layer of TMR element 105 on TMR lowerelectrode 158 on oxide film 126 b.

(5) Pattern TMR element 105.

(6) Pattern the metallic thin film formed above (3), and form TMR lowerelectrode 158.

(7) Deposit oxide film 133 on the whole surface.

(8) Form selectively via hole 140 which penetrates oxide film 133, andthe formation area of upper Cu wiring 134.

(9) Do CMP treatment after embedding and depositing upper Cu wiring 134.

It supposes that the above-mentioned step of (6) is called LS step, andthere is a problem shown below in this LS step.

FIG. 47-FIG. 49 are the cross-sectional views showing LS step foracquiring via hole LS connection structure (referring to FIG. 46).Hereafter, LS step is explained with reference to these drawings.

As shown in FIG. 47, lower Cu wiring 125 (read wire 125 r, digit line125 d) which penetrates oxide film 124 is selectively formed after theoxide film 124 formation formed above the semiconductor substrate. Afterforming silicon nitride film 126 a and oxide film 126 b in the wholesurface, via hole 109 which penetrated silicon nitride film 126 a andoxide film 126 b, and used a part of read wires 125 r as the bottom isformed. After forming TMR lower electrode 158 on the bottom and the sidesurface of via hole 109, and oxide film 126 b, TMR element 105 (TMR film129, TMR upper electrode 131) is obtained. After forming resist 155 inthe whole surface, resist 155 is patterned by forming opening 156 forseparating TMR lower electrode 158 per element.

And as shown in FIG. 48, TMR lower electrode 158 is patterned by etchingTMR lower electrode 158 by using resist 155 as a mask. Then, ashingtreatment removes resist 155.

On this occasion, as shown in FIG. 48, there is a source of anxiety withwhich side wall reaction part 159 which includes a polymer, a magneticfilm, etc. by the reaction in the side wall of TMR film 129 is formed.As shown in FIG. 49, at via hole bottom end portion region 171 of viahole 109, there was a source of anxiety that a part of lower Cu wiring125 (read wire 125 r) under TMR lower electrode 158 corrodes, and Cucorrosion part 160 generates from a part of ultra thin film formationparts of TMR lower electrode 158, or non-film formation part 168.

Such a source of anxiety originates in the ability of TMR lowerelectrode 158 for covering nature not to improve embedded formation invia hole 109 from a reason with the point which embeds and forms a partof TMR lower electrodes 158 in via hole 109, and the point which hasrestrictions in the thickness of TMR lower electrode 158. Thatrestrictions occur in the thickness of TMR lower electrode 158 isbecause the thickness of TMR lower electrode 158 used as the foundationlayer of TMR element 105 is restricted to 100 nm or less since thecharacteristics are influenced by the roughness of TMR lower electrode158 which is a foundation layer as to TMR element 105 formed on TMRlower electrode 158.

Therefore, since a possibility that an ultra thin film formation part ornon-film formation part 168 will occur in TMR lower electrode 158 at viahole bottom end portion region 171 is high, the source of anxiety of Cucorrosion from an ultra thin film formation part or non-film formationpart 168 to lower Cu wiring 125 cannot be disregarded at the time ofashing of resist 155.

As a result, electric connection between TMR lower electrode 158 andread wire 125 r could not fully be made by realization of theabove-mentioned source of anxiety, but there was a problem of resultingin a wiring failure. Embodiment 3 aimed at the settlement of thisproblem.

Structure of Embodiment 3

FIG. 50 is a cross-sectional view showing the structure of the memorycell part of MRAM which is a semiconductor device of Embodiment 3 ofthis invention. In FIG. 50, the structure where TMR element 105 (firstand second TMR element) of the same structure is formed in two TMRformation areas 103,104 (first and second TMR formation area),respectively is shown.

As shown in the same drawing, oxide film 124 which is first interlayerinsulation film is penetrated, and read wire 125 r and digit line 125 dwhich form lower Cu wiring 125 (lower layer wiring) selectively areformed in each of TMR formation area 103,104. Although MRAM ofEmbodiment 3 as well as MRAM of Embodiment 1 is formed abovesemiconductor substrate 100 by a laminated structure, the drawing showsand explains only the superstructure from oxide film 124 on account ofexplanation. Oxide film 124 is equivalent to interlayer insulation film24 (references, such as FIG. 3) of Embodiment 1.

And silicon nitride film 126 a (first partial interlayer insulationfilm) and oxide film 126 b (second partial interlayer insulation film)which includes SiO₂ are laminated on oxide film 124 including lower Cuwiring 125, and silicon nitride film 126 a and oxide film 126 b form thesecond interlayer insulation film.

In each of TMR formation area 103,104, via hole 109 (local via hole) isformed in interlayer insulation films 126 a and 126 b which correspondto a part of formation area of read wire 125 r in plan view. Byselectively forming TMR lower electrode 128 used as LS on interlayerinsulation film 126 b, and the bottom and the side surface of via hole109, in each of TMR formation area 103,104, TMR lower electrode 128 iselectrically connected with read wire 125 r.

TMR lower electrode 128 (first lower electrode) of TMR formation area103 and TMR lower electrode 128 (second lower electrode) of TMRformation area 104 are mutually separated by opening 147 (distance d1)formed in TMR formation area 103,104 boundary and its neighboringregion.

TMR element 105 (TMR film 129, TMR upper electrode 131) is selectivelyformed in the region which corresponds in plan view on each TMR lowerelectrode 128 of TMR formation area 103,104 in a part of formation areaof digit line 125 d. TMR film 129 includes the laminated structure offerromagnetic layer 129 a, nonmagnetic layer 129 b, and ferromagneticlayer 129 c from the upper part, for example.

And the upper surface of TMR lower electrode 128, and the side surfaceand the upper surface of TMR element 105 are covered, and insulatingfilm 130 is formed. As insulating film 130, a nitride film (SiN), anoxide film (SiO₂, GeO, Al₂O₃), etc. can be considered.

Insulating film 130 is formed using the insulating material formed atthe low temperature less than 300° C. For example, a nitride film formedat low temperature (LT (Low Temperature)−SiN) etc. can be considered asinsulating film 130.

And the whole surface including insulating film 130 is covered, andoxide film 133 which includes SiO₂ and is third interlayer insulationfilm is formed. On this occasion, oxide film 133 is formed of thematerial with same chemical species with oxide film 126 b. Oxide film133 is completely manufactured by the manufacturing process of the samecontents with oxide film 126 b.

Insulated separation of TMR lower electrode 128 of TMR formation area103 and the TMR lower electrode 128 of TMR formation area 104 isthoroughly done by forming oxide film 133 also in opening 147.

Upper Cu wiring 134 used as a bit line is selectively formed in theupper layer portion of oxide film 133. At the region in which TMRelement 105 is formed in plan view in each of TMR formation area103,104, oxide film 133 and insulating film 130 are penetrated, and viahole 140 is formed, By embedding upper Cu wiring 134 also in this viahole 140, upper Cu wiring 134 and TMR upper electrode 131 areelectrically connected.

As mentioned above, it is assuming the via hole LS connection structurewhich electrically connects lower Cu wiring 125 (read wire 125 r) andTMR element 105 (TMR film 129) by forming TMR lower electrode 128 in viahole 109.

(Effect)

FIG. 51 is a cross-sectional view showing the effect of thesemiconductor device of Embodiment 3. Since insulating film 130 isformed on TMR lower electrode 128 in via hole 109 even if ultra thinfilm formation part or non-film formation part 148 occurs in a part ofTMR lower electrodes 128 in via hole bottom end portion region 107 asshown in the same drawing, when performing ashing treatment of theresist used for the patterning of TMR lower electrode 128 in LS stepafter LS step, it can avoid surely that Cu corrosion advances from ultrathin film formation part or non-film formation part 148 to lower Cuwiring 125 (read wire 125 r) at the time of ashing treatment.

Therefore, Cu corrosion part 160 as shown in FIG. 49 does not occur, andgood electric connecting relation is collateralized between TMR lowerelectrode 128 and read wire 125 r, and the effect that improvement inthe yield is expectable is performed.

The effect mentioned above can be demonstrated also in the structure(references, such as FIG. 2) of Embodiment 1 where interlayer insulationfilm 30 is formed on TMR lower electrode 28.

Since the side surface of TMR lower electrode 128 and insulating film130 in the neighboring region of opening 147 is almost matched, themicrofabrication effect of distance d1 between TMR lower electrodes 128formed in each of TMR formation area 103,104 by newly forming insulatingfilm 130 not spreading, and not spoiling an integration degree isperformed.

That is, since the side surface of TMR lower electrode 128 is matched tothe side surface of insulating film 130, even if it patternssimultaneously insulating film 130 and TMR lower electrode 128 so thatit may mention later, it does not have a bad influence on the workingshape of TMR lower electrode 128.

In addition, since the low-temperature insulation film formed at the lowtemperature less than 300° C. as insulating film 130 is used, by forminginsulating film 130 at the low temperature less than 300° C., theperformance degradation of TMR element 105 at the time of formation ofinsulating film 130 can be prevented surely. Namely, it does not have abad influence on the characteristics of TMR element 105 at the time offormation of insulating film 130. As a result, compared with the casewhere the insulating film which results more than 300° C. is formed, thespin orientation improvement of a magnetic multilayer film, the switchedconnection improvement between magnetic multilayer films, and reductionof heat stress are expectable regarding TMR film 129.

The effect mentioned above can be demonstrated also in the structure(references, such as FIG. 2) of Embodiment 1 which forms interlayerinsulation film 30 formed from LT-SiN on TMR lower electrode 28.

FIG. 52 and FIG. 53 are graph which shows the effect at the time offorming insulating film 130 from a low-temperature formation insulatingmaterial. FIG. 52 shows the annealing temperature dependency of coerciveforce Hc of TMR element 105, and FIG. 53 shows the annealing temperaturedependency of anisotropic magnetic field Hk of TMR element 105. Anequivalent for the forming temperature of insulating film 130 is alsoincluded in these temperature zones. In FIG. 52 and FIG. 53, L1 showsthe case where the thickness of ferromagnetic layer 129 a is 3 nm, andL2 shows the case where the thickness of ferromagnetic layer 129 a is 5nm.

In the region in which formation of insulating film 130 exceeds 300° C.as shown in FIG. 52, the inclination of coercive force Hc over thetemperature change of TMR element 105 becomes steep, and it becomes verydifficult to set up coercive force Hc with sufficient accuracy. In theregion in which formation of insulating film 130 exceeds 300° C. asshown in FIG. 53, the inclination of anisotropic magnetic field Hk tothe temperature change of TMR element 105 becomes higher, and it becomesdifficult to set up anisotropic magnetic field Hk with sufficientaccuracy.

Thus, when processing which exceeds 300° C. after formation of TMRelement 105 is performed, it becomes difficult to control the magneticproperty of TMR element 105 with sufficient accuracy, and a possibilitythat magnetic property will deteriorate is high as a result.

However, in MRAM of Embodiment 3, magnetic property degradation of TMRelement 105 can be effectively suppressed by forming insulating film 130at the low temperature less than 300° C. using a low-temperatureformation insulating material.

Since insulating film 130 is formed all over TMR lower electrode 128upper part also in TMR peripheral region 108 on oxide film 126 b inwhich TMR element 105 is not formed as shown in FIG. 54, the antioxidanteffect in TMR lower electrode 128 front surface and the improvement(resistance reduction) effect of the electrical property of TMR lowerelectrode 128 are expectable at the time of LS step.

The effect mentioned above can be demonstrated also in the structure(references, such as FIG. 2) of Embodiment 1 which forms interlayerinsulation film 30 on TMR lower electrode 28 on interlayer insulationfilm 26 b with which TMR element 5 is not formed.

In addition, by forming oxide film 126 b and oxide film 133 with thesame material (SiO₂) in chemical species as shown in FIG. 55, ininsulating region 136 between straps, interface 137 which oxide film 126b and oxide film 133 of the same material contact is formed.

For example, it is expected that when the interface of a nitride filmand an oxide film exists, the defect in an interface will betransmitted, and in TMR formation area 103,104, leakage current flowsbetween TMR lower electrodes 128,128 which adjoin mutually. This leakagecurrent poses a remarkable problem as the microfabrication of equipmentprogresses.

However, since the defect in interface 137 can be surely reduced inEmbodiment 3 by forming chemical species for oxide film 126 b and oxidefilm 133 with the same material, the above-mentioned leakage current canbe reduced effectively and improvement in the yield can be expected. Inaddition, the effect of making microfabrication of equipment possible isperformed.

Although the case where oxide film 126 b and oxide film 133 were SiO₂was mentioned as the example in both these embodiments, of course, othermodes, such as a low-k film of the same material, are sufficient.

Since oxide film 126 b and oxide film 133 are formed by themanufacturing process of the same contents in Embodiment 3,respectively, the above-mentioned leakage current suppression effect canbe demonstrated further, and the further improvement in the yield and amicrofabrication facilitatory effect can be expected.

(Other Modes)

By forming only from a low-k film formed at low temperature as oxidefilm 133 with which between TMR lower electrodes 128,128 in TMRformation area 103,104 is insulated, the capacity between wiringsgenerated between TMR lower electrodes 128,128 is reduced, andhigh-speed operation becomes possible.

FIG. 56 is a cross-sectional view showing other modes of Embodiment 3.As shown in the same drawing, when the end portion of TMR lowerelectrode 128 oxidizes, in strap insulation end portion region 138, itis end portion oxidization region 132.

Thus, in other modes of Embodiment 3, the end portion side surface ofTMR lower electrode 128 in strap insulation end portion region 138 willbe located inside insulating film 130 by existence of end portionoxidization region 132. As a result, the effect which can increase theinsulation between TMR lower electrodes 128,128 (between the first andsecond lower electrodes) in TMR formation area 103,104 is performed,without spoiling the integration degree of equipment. Since end portionoxidization region 132 is sufficiently small to TMR lower electrode 128,the conductivity of TMR lower electrode 128 does not deteriorate by endportion oxidization region 132.

When forming end portion oxidization region 132, it is desirable to formTMR lower electrode 128 from material with which it is high meltingpoint metals, such as titanium (Ti) and Ta, and an oxide has insulation.For example, tantalum oxide (Ta₂O₅) can be formed as end portionoxidization region 132 from the end portion of TMR lower electrode 128by forming TMR lower electrode 128 by Ta at the time of ashingtreatment.

Thus, by forming TMR lower electrode 128 of Ti, Ta, etc. of thecharacteristics mentioned above, in addition to the insulated effectbetween TMR lower electrodes 128,128 by end portion oxidization region132 mentioned above, the nonproliferation effect of TMR lower electrode128 forming material in a manufacturing process is performed.

(Manufacturing Method)

FIG. 57-FIG. 63B are the cross-sectional views showing a part ofmanufacturing method of MRAM of Embodiment 3. “A” in FIG. 62 and FIG. 63shows the section of a memory circuit region, and “B” of these drawingsshows the section of the peripheral circuit area. Hereafter, themanufacturing method of MRAM of Embodiment 3 is explained with referenceto these drawings.

First, the structure shown by FIG. 57 is acquired by the same method asEmbodiment 1. That is, lower Cu wiring 125 (read wire 125 r, digit line125 d) which penetrates oxide film 124 formed above the semiconductorsubstrate which is not illustrated, and is formed selectively isobtained. Then, silicon nitride film 126 a, and oxide film 126 b whichincludes SiO₂ are formed in the whole surface one by one, the portion onthe region of read wire 125 r in a memory circuit region is penetrated,and via hole 109 is formed selectively.

And the layer which should constitute TMR lower electrode 128, TMR film129, and TMR upper electrode 131 is laminated on the whole surface. Onthis occasion, TMR lower electrode 128 is electrically connected withread wire 125 r by forming TMR lower electrode 128 in the bottom and theside surface of via hole 109. Then, TMR upper electrode 131 and TMR film129 are patterned, and TMR element 105 is completed.

And as shown in FIG. 58, after forming in the whole surface insulatingfilm 130 which includes LT-SiN by the low temperature condition lessthan 300° C., patterned resist 145 which has opening 146 in a TMRformation area 103,104 boundary neighboring region is formed. On thisoccasion, the thickness of insulating film 130 is formed by thicknesscomparable as the thickness of silicon nitride film 126 a at about 60nm.

Thus, in the manufacturing method of MRAM of Embodiment 3, sinceinsulating film 130 is formed at the low temperature less than 300° C.,it does not have a bad influence on the characteristics (refer to FIG.52 and FIG. 53) of TMR element 105 at the time of insulating film 130formation.

The effect mentioned above can be demonstrated also in the manufacturingmethod (references, such as FIGS. 16A to 16D) of Embodiment 1 whichforms in the whole surface interlayer insulation film 30 which includesLT-SiN by the low temperature condition less than 300° C.

And as shown in FIG. 59, by performing reactive ion etching (ReactiveIon Etching; RIE) to insulating film 130 and TMR lower electrode 128using patterned resist 145 as a mask, insulating film 130 and TMR lowerelectrode 128 are patterned continuously. Thus, since insulating film130 and TMR lower electrode 128 are continuously etched by resist 145,in immediately after etching, the side surface of insulating film 130and TMR lower electrode 128 in opening 147 is almost matched.

As a result, TMR lower electrode 128, TMR element 105, and insulatingfilm 130 (the first lower electrode, the first TMR element, the firstinsulating film) in TMR formation area 103 (first TMR formation area)and TMR lower electrode 128, TMR element 105, and insulating film 130(second lower electrode, second TMR element, second insulating film) inTMR formation area 104 (second TMR formation area) will be formedindependently each other.

And the above first and second insulating films have side surfaces whichseparate each other by distance d1 (prescribed interval) and face. Theabove first and second lower electrode have side surfaces which separatedistance d1 mutually and face. That is, as for the above firstinsulating film and the above first lower electrode (TMR lower electrode128 and insulating film 130 in TMR formation area 103), in the uniformdirection (first direction) which goes to TMR formation area 104 fromTMR formation area 103, the side surface formation position corresponds.As for the above second insulating film, and the above second lowerelectrode (TMR lower electrode 128 and insulating film 130 in TMRformation area 104), in the uniform direction (second direction) whichgoes to TMR formation area 103 from TMR formation area 104. the sidesurface formation position corresponds. In this embodiment, the sidesurface formed when it etches continuously using the same mask patternis meant as a side surface matching. That is, the distance (Distancebetween the side surfaces in the identical direction (first direction)which goes to TMR formation area 104 from TMR formation area 103 when alevel difference occurs on the side surface of TMR lower electrode 128and insulating film 130 in TMR formation area 103) in the firstdirection of the first above-mentioned insulation film and the sidesurface of the first above-mentioned lower electrode is smaller than thedistance between the side surfaces of the side surface at the side ofopening 147 of TMR element 129, and TMR lower electrode 128 formed usinga mask pattern different, for example.

Then, as shown in FIG. 60, ashing treatment removes resist 145. As aresult, in TMR formation area 103,104 respectively, the structure whoseside surface of TMR lower electrode 128 and insulating film 130 in anidentical direction almost matched can be acquired.

When TMR lower electrode 128 is formed on the other hand with themetallic material with which it is high melting points, such as Ti andTa, and an oxide has insulation, as shown in FIG. 61, in an ashingtreatment stage, TMR lower electrode 128 oxidizes from the exposure sidesurface in opening 147, and end portion oxidization region 132 isformed.

Namely, by oxidizing in part from the side surface of the above firstand second lower electrode by ashing treatment, end portion oxidizationregion 132 (first and second end portion oxidization region) is formedin TMR formation areas 103 and 104 respectively. With formation of endportion oxidization region 132, the above side surface of the first andsecond lower electrode is become depressed and formed in the first andsecond direction to the side surface of the above first and secondinsulating film.

Thus, since the above first and second end portion oxidization region isformed by oxidizing in part from the side surface of the above first andsecond lower electrode by the ashing treatment at the time of removal ofresist 145, the insulation between the first and second above-mentionedlower electrodes can be increased further.

Resist 145 is surely removable by performing wet screening after ashingtreatment. On this occasion, since insulating film 130 is formed on TMRlower electrode 128, trouble does not occur in TMR lower electrode 128at the time of wet washing (cleaning).

Thus, since ashing treatment and a wet cleaning treatment are performedas removal disposal of resist 145, resist 145 is removable withsufficient accuracy. On this occasion, since insulating film 130 isformed on TMR lower electrode 128, it does not have a bad influence onthe execution time of ashing treatment and wet washing at TMR lowerelectrode 128, and read wire 125 r in the via hole 109 bottom.

Since the manufacturing method of the semiconductor device of Embodiment3 used resist 145 as the mask, TMR lower electrode 128 and insulatingfilm 130 were etched continuously and TMR lower electrode 128 andinsulating film 130 are patterned, as mentioned above, as a result fromwhich TMR lower electrode 128 of via hole 109 is protected by insulatingfilm 130 after processing of TMR lower electrode 128, in the removingprocessing (ashing treatment, wet cleaning treatment) stage of resist145, the damage to read wire 125 r under via hole 109 can be avoided,and improvement in the yield of the completed semiconductor device canbe aimed at.

The effect mentioned above can be demonstrated also in the manufacturingmethod (references, such as FIGS. 18A to 18D and FIGS. 19A to 19D) ofEmbodiment 1 with which interlayer insulation film 30 is formed on TMRlower electrode 28 at the time of removal of resist 45 after etchingsimultaneously TMR lower electrode 28 and interlayer insulation film 30by using resist 45 as a mask.

Next, after forming in the whole surface oxide film 133 which includesSiO₂, as shown in FIG. 62A, via hole 139 (partial via hole for TMR)which penetrates oxide film 133 is formed at the upper part of TMRelement 105 in a memory circuit region. As shown in FIG. 62B, via hole149 (partial via hole for the circumferences) which penetrates oxidefilm 133 and oxide film 126 b in the upper layer of a part of lower Cuwiring 125 in a peripheral region is formed. On this occasion,insulating film 130 functions as a stopper of via hole 139 formation,and silicon nitride film 126 a functions as a stopper of via hole 149formation.

Thus, since oxide film 133 is formed with the material which differsfrom chemical species with insulating film 130 and silicon nitride film126 a which are silicon nitride films and formed with the material(SiO₂) whose chemical species are the same as oxide film 126 b, byoperating as a stopper insulating film 130 and silicon nitride film 126a of material (different material) with which oxide film 133 and oxidefilm 126 b differ from chemical species, even if it forms simultaneouslyvia hole 139 and via hole 149, via holes 139 and 149 can be formed withrespectively sufficient accuracy.

At the upper part of TMR element 105, as shown in FIG. 63A, via hole 140(via hole for TMR) which also penetrates insulating film 130 from viahole 139 in a memory circuit region is formed. In a peripheral region,simultaneously with it, as shown in FIG. 63B, via hole 150 (via hole forthe circumferences) which also penetrates silicon nitride film 126 afrom via hole 149 is formed.

On this occasion, by forming the thickness of insulating film 130 whichis a silicon nitride film and the thickness of silicon nitride film 126a which is the same material in chemical species to the same extent,even if it forms via hole 140 and via hole 150 simultaneously, via holes140 and 150 can be formed with respectively sufficient accuracy.

As a result, since via hole 140 and 150 can be formed simultaneously,reduction of the manufacturing cost accompanying simplification of amanufacturing process can be aimed at.

And a bit line is formed by embedding upper Cu wiring 134 in via hole140 and 150. As a result, in a memory circuit region, upper Cu wiring134 is electrically connected with TMR element 105 (TMR upper electrode131) via via hole 140, and upper Cu wiring 134 is electrically connectedwith lower Cu wiring 125 in a peripheral circuit area. Thus, MRAM (aperipheral circuit is included) of Embodiment 3 is completed.

1. A semiconductor device, comprising: a first interlayer insulationfilm formed above a semiconductor substrate; a lower layer wiring formedselectively to penetrate the first interlayer insulation film; a secondinterlayer insulation film formed over the first interlayer insulationfilm and the lower layer wiring and having a via hole exposing an uppersurface of the lower layer wiring; a lower electrode formed at a bottomand a side surface of the via hole and over the second interlayerinsulation film, the lower electrode being electrically connected withthe lower layer wiring via the via hole; a TMR element, formedselectively over a portion of the lower electrode and including alaminated structure of a TMR film and an upper electrode; insulatingfilm formed over the lower electrode, the TMR element and an inside ofthe via hole, wherein the semiconductor device has a first TMR formationarea and a second TMR formation area, and the TMR element, the lowerelectrode, and the insulating film are formed in each of the first andthe second TMR formation areas, wherein both the insulating film and thelower electrode have a side surface over the second interlayerinsulation film in a uniform direction of an adjacent another lowerelectrode mutually, and wherein a side surface of the lower electrodecorresponds in a uniform direction to a side surface of the insulatingfilm, or a side surface of the lower electrode is depressed from theinsulating film; and a third interlayer insulation film formed over theinsulation film in the first and the second TMR formation areas, whereinthe third interlayer insulation film is in contact with the secondinterlayer insulation film between the first and the second TMRformation areas to separate the lower electrodes and the insulatingfilms in the first and the second TMR formation areas.
 2. Asemiconductor device according to claim 1, wherein the insulating filmincludes a low-temperature insulation film formed at a low temperatureless than or equal to 300° C.
 3. A semiconductor device according toclaim 1, wherein the insulating film is formed over a whole surface overthe lower electrode over the second interlayer insulation film.
 4. Asemiconductor device according to claim 1, wherein a side surface of thelower electrode is formed to correspond to a side surface of theinsulating film in the uniform direction.
 5. A semiconductor deviceaccording to claim 1, wherein chemical species of the second and thirdinterlayer insulation films are formed with the same material.
 6. Asemiconductor device according to claim 5, wherein the second and thirdinterlayer insulation films are formed by the manufacturing process ofthe same contents.
 7. A semiconductor device according to claim 6,wherein the second and third interlayer insulation films are,respectively, formed in an interface and its neighborhood by alow-temperature insulation film formed at a low temperature less than300° C. at least.
 8. A semiconductor device according to claim 1,wherein the lower electrode has an end portion oxidization regionadjoining a side surface of the lower electrode.
 9. A semiconductordevice according to claim 8, wherein the lower electrode includes ametallic material which has a high melting point, and an oxide havinginsulation.